The Angola National Urbanisation and Housing Program (PNUH), launched in 2008, aimed to build one million new housing units, according to the World Bank. However, by 2024, it had delivered only approximately 220,000. Power2Build, an Angolan construction startup, estimates the current housing deficit in Angola to be around three million homes, with the situation particularly critical in Luanda, one of the fastest-growing cities on the African continent. With an entirely Angolan multidisciplinary team, Power2Build aims to contribute to reducing this deficit through the use of automated 3D concrete printing technology.
Implemented on-site with large-scale construction printers from Danish company COBOD, the system is expected to accelerate construction timelines and improve building quality. Large-scale cement-based 3D printing eliminates the need for traditional moulds by precisely placing or solidifying specific volumes of material in sequential layers using computer-controlled positioning. The process involves three key stages: data preparation, material preparation, and printing.
In the data preparation stage, a 3D form is sliced into thin, flat layers of constant thickness, which can then be stacked sequentially. Each layer typically consists of a contour and an internal fill pattern, such as honeycomb structures or space-filling curves. An alternative method uses tangential continuity, generating construction paths with locally varying thicknesses. This method optimises the printing process by ensuring continuous contact between layers, avoiding geometric gaps hindering print quality and structural performance.
The next phase involves material preparation. Power2Build uses locally sourced materials and conventional cement in its concrete mix, which includes Cement 42.5 N, fine sand, gravel (4/6 mm), the D. Fab Alfa plasticiser additive, the D. Fab Beta additive for consistency, and Isoxel as a hardener. Once the mix is prepared, it is placed into a container, which is transported via a nozzle-pump system to produce self-compacting concrete filaments. The material's pump ability and extrusion stability depend on the specific concrete mix, delivery system, and nozzle configuration.
Structural housing components are manufactured via additive construction. The printing system must be controlled by either a gantry setup or a robotic arm. A gantry system positions the nozzle within an XYZ coordinate framework, while robotic arms provide additional degrees of freedom, enabling advanced techniques such as tangential continuity printing. Integrating these systems into mass housing construction reshapes the labour landscape, reducing manual masonry work while increasing the demand for specialised labour in the planning and finishing phases.
Power2Build's housing projects in Angola are constructed using the second-largest 3D printer in the world. COBOD's BOD2 series printers feature a modular structure composed of 2.5-meter-long units, offering a maximum build volume of 10 meters in height (up to two stories), 15 meters in width, and 45 meters in length. These printers operate between 100 mm/s and 500 mm/s, with an optimal speed of 250 mm/s. Assembly and disassembly times are approximately 4-6 hours and 3-4 hours, respectively. The newer BOD3 model uses similar modular units on rails for enhanced mobility. It allows printing heights up to 15 meters (three stories), with the same width and a slightly reduced length of 40 meters. It also offers faster assembly and disassembly times, 3-4 hours and 2-3 hours, respectively.
